Flat bottomed hulls are considered to have good planing characteristics due to the fact that there is a minimum amount of wetted surface and as a result there is a minimum drag as the speed is increased. However, flat bottomed hulls lack stability on turning and also have a tendency to produce a rough ride in choppy water.
V-bottom hulls are generally formed with a relative deep V at the bow which flattens out toward the stern. The V-hull has the advantage of being able to cut into heavy seas, although as the V cuts down into the water the water is displaced upwardly along the V and has a tendency to slap against the bottom of the hull. Furthermore, the V-bottom hull lacks lateral stability particularly in the forward areas.
More recently the tri-hull has become more popular in smaller boats. The tri-hull consists of a central V along with V's of lesser depth along the side edges of the hull. The tri-hull provides a substantial increase in lateral stability, particularly in the forward areas, but acts to increase the amount of wetted surface so that the planing characteristics of the tri-hull are adversely effected.
Various other types of modified V-hulls or tri-hulls have been used in the past in an attempt to obtain better planing characteristics or to increase the stability of the hull.